1. Field of the Invention
This invention relates to a mechanism for setting slip and/or camber angles in a tire testing machine.
2. Description of the Prior Art
For testing various characteristics of tires, for instance, reliability and durability at high speeds, there have been in use tire testing machines of the type in which a tire to be tested is contacted with a circumferential surface of a rotating wheel acting as a substitutional road, applying a radial load on the tire which is held in straight-forward position. However, tires which are actually mounted on vehicle wheels are imparted with slip angles to the left and right from the travel direction of the vehicle as a result of the steering operation by the driver or with camber angles depending upon the road condition. Therefore, in order to test a tire in conditions akin to actual running condition, a tire testing machine should include a mechanism for turning or tilting the tire being tested in simulation of the slip and camber angles.
In this regard, there have been proposed and in use various tire tilting devices, including the following two types. In the first type, a slip or camber angle is imparted by turning a tire about the center of its tread which is in contact with the rotating wheel or substitutional road. In the other type, a slip or camber angle is imparted by turning a tire about a point which is located at a distance from the center of the tread of the tire being tested. Of these two types of tire tilting devices, the first type which is adapted to effect the turns for the slip and camber angles by rotation about the center of the tread is closer to actual running conditions and more preferable in view of the curvature of limited radius of the substitutional rotating wheel. However, this type of angle setting mechanism usually has an uneconomically large size due to the necessity for turning or tilting the tire about the center of its tread.
On the other hand, the second type angle setting mechanism in which the tire is turned about a point which is located at a certain distance from the center of the tire is more economical as it is smaller in size and simpler in construction. However, the second type has an inherent problem in that the center of the tire tread is deviated along the rotating wheel upon making a turn for the slip angle and application of accurate radial load sometimes becomes difficult due to the adverse effects resulting from deviation along the curvature of the rotating wheel.